Compounds of the following structure are described collectively in Great Britain Pat. No. 945,856 and U.S. Pat. No. 3,300,532: ##STR3## wherein each W represents hydrogen, halogen, or alkoxy; W.sub.1 represents hydrogen or alkoxy with the proviso that each of W and W.sub.1 may not represent hydrogen at the same time; and W.sub.2 and W.sub.3 represent alkyl.
Compounds of the above structure wherein the moiety --(CH.sub.2)--.sub.1-5 is a branched chain are disclosed in Netherlands application No. 7212967 as analgesics. To applicants' knowledge neither the compounds of the above structure nor the compounds of the Netherlands application has been suggested or taught previously for use in treating sickle cell anemia.